Within the context of an oil rig operation, it has become necessary within the past fifteen years to conduct wireline operations, wherein a wireline unit disposed adjacent to the rig floor drives a steel cable, or wireline as it referred to in the oil industry, around a pulley wheel mounted at the top of the oil derrick, the wireline then traveling downwardly within the oil derrick towards the rig floor and ultimately down the pack-off assembly which is connected on its bottom end to the circulating head which is mated on its bottom end with the drill pipe. Simply stated, the primary function of the wireline is to "steer" the drill pipe for directional drilling wherein a bent sub is connected to the bottom of the bottommost drill pipe in the wellbore, the bent sub having a drilling bit mounted to its outer end for drilling; the wireline is driven or "shot" down the pack-off assembly and down the drill pipe until it connects with a mechanism which guides or "steers" the bent sub to facilitate drilling in the proper direction. The wireline is also similarly "shot" down the drill pipe to "fish" for "junk" which has fallen down or otherwise lodged itself within any part of the drill pipe, generally at the bottom thereof, the "junk" usually consisting of broken drilling bits, tools, or materials that have been accidentally dropped into the drill pipe, etc. Wireline is employed to retrieve the "junk" therefrom so that drilling or other operations can be resumed.
Wireline operations have been plagued from the beginning by problems largely due to damaged and frayed wireline which is caused by the wireline rubbing against the cable travelling around the crown block at the top of the oil derrick and therefrom up and down within the oil derrick, and against the swivel known in the oil industry as the travelling block, attached to the cable. This rubbing action is due to the angle at which the wireline travels within the oil derrick after being driven from the wireline unit around the pulley wheel positioned at the top of the oil derrick. Furthermore, because of this angle, as the wireline is "shot" or driven down the pack-off assembly, the circulating head, and the drill pipe, the wireline rubs against the packing nut of the pack-off assembly and after a short period of time cuts a groove into the packing nut, which is the top part of the pack-off assembly, and cuts a groove into a plurality of pack-off seals mounted within the lower body of the pack-off assembly for preventing the upflow of circulating fluids from the circulating head through the pack-off assembly and onto the rig floor. Within a short period of time, the pack-off seals become damaged by the cutting/rubbing action of the wireline to such an extent that they become irrepairably damaged, thereby permitting the upflow of circulating fluids from the circulating head through the pack-off assembly and onto the rig floor. Drilling operations must be stopped while the rig floor is cleaned and to replace the pack-off seals which have been ruined; not only is the spilled fluid messy, but it is easily discernible that it can cause injuries to workmen working on the rig floor. Therefore, because of the damage to the pack-off seals, costs are incurred to replace the seals and the rig is temporarily shutdown at great cost due to the high cost of labor and the high rental cost of the rig and operating equipment, tools, and materials that merely lay idle during this shutdown period. The primary cause of concern, however, is the damage occasioned to the wireline by the rubbing of the wireline against the cable and travelling block. Wireless oftentimes travels down the drill pipe to depths of 25,000 ft., depending, of course, upon the depth of the wellbore. The wireline begins to "strand" or fray after rubbing for some time against the cable, travelling block, and pack-off assembly, and this damage dangerously weakens the wireline, eventually irreparably damaging the wireline, rendering it unfit for further use. Wireline has been used for approximately 1 to 150 "trips" in the past, a "trip" being defined as the movement of the wireline up and down within the drill pipe one time. The present invention has for its primary object the prevention of this rubbing action between the wirelines and the cable, travelling block, and pack-off assembly, thereby preventing the fraying of and damage to the wireline and extending the average useful life of the wireline to over 300 "trips," a marked improvement over the present approximately 50 "trips" average useful life of wireline. When the wireline becomes so damaged that it must be replaced, great expenses and delays are incurred. Wireline usually must be shipped out to the platform in the case of offshore oil operations or trucked out to an onshore oil rig, resulting in fairly heavy costs and requiring a shutdown of the oil rig and the consequent costs involved therewith because of the high cost of materials and labor laying idle during this shutdown period. The wireline itself costs between $10,000 to $20,000 to replace. It is easy to perceive how valuable the apparatus of the present invention will be to the oil industry.